Centrifuge rotor with removable trunnion pins

ABSTRACT

A centrifuge rotor having a core with outwardly extending support arms having removable trunnion pins for supporting a carrier.

I United States Patent 1 [111 3,722,791

Wright 1 Mar. 27, 1973 [54] CENTRIFUGE ROTOR WITH [56] References Cited REMOVABLE TRUNNION PINS UNITED STATES PATENTS [751 Invent: Herschel wrigh" Clara, 3,028,075 4/1962 Blum ..233/26 Calif. FOREIGN PATENTS OR APPLICATIONS [73] Assigneez Beckman Instruments, Inc., Fullerton Calif 527,712 10/1940 Great Britain ..233/26 925,817 3/1955 Germany ..233/26 [22] Filed: Apr. 3, 1972 Primary ExaminerJames R. Boler [21] Appl' 240340 Assistant Examiner-George I-I. Kritzmanich Att0rney--Paul D. Flehr et al.

[52] U.S.Cl ..233/26 57 ABSTRACT [51] m;'oi;..:...; pom/I2, 1 [58] Field of Search ..23/292; A entrifuge rotor having a core with ou wardly extending support arms having removable trunnion pins for supporting a carrier.

3 Claims, 5 Drawing Figures AwEr-umazm SHEET 10F 2 PATENIEDmznm ,722,791

SHEET 2 BF 2 CENTRIFUGE ROTOR WITH REMOVABLE TRUNNION PINS BACKGROUND-OF THE INVENTION This invention relates generally to centrifuge rotors and more particularly to centrifuge rotors having support arms including removable trunnion pins for supporting swinging buckets or carriers.

Centrifuge rotors including carriers supported on trunnion pins disposed at the ends of outwardly extending arms have included both integral and separable or removable trunnions. Rotors with integral trunnions are relatively expensive to manufacture. Rotors with removable trunnion pins of the prior art have necessitated the separation of pairs of pins mounted at the end of each arm to permit assembly of the pins into the arms such as by press fitting or threading the pins into the arms. The assembly is relatively complicated and expensive.

OBJECTS AND SUMMARY OF THE INVENTION It is a general object of the present invention to provide an improved centrifuge rotor with removable trunmon pins.

It is another object of the present invention to provide a centrifuge rotor including outwardly extending spaced arms which accommodate removable trunnion pins which cooperate with one another under centrifugal forces.

It is another object of the present invention to provide a rotor which is relatively simple and inexpensive to manufacture.

It is still another object of the present invention to provide a centrifuge rotor in which the trunnion pins bear against a large bearing area of the rotor arms.

The foregoing and other objects are achieved by a centrifugal rotor assembly comprising a core for mounting the rotor on a drive shaft which rotates the rotor about its axis of rotation, a plurality of spaced arms which extend radially outward from the axis of the rotor with the ends of each of the arms including a pair of intersecting holes which also lie in a plane perpendicular to the axis of rotation. A pair of trunnion pins is inserted in the intersecting holes and is adapted to have one end of each cooperate with one another for locking in the rotor arms with the other end of the pins of ad jacent arms extending in line towards one another to form trunnions to receive a carrier.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view showing a centrifuge rotor with outwardly extending arms and trunnion pins in accordance with the invention supporting carriers.

FIG. 2 is a plan view of the rotor shown in FIG. 1.

FIG. 3 is an enlarged view of the end of one of the arms of the rotor showing the trunnion pins inserted therein.

FIG. 4 is a view taken along the line 4-4 of FIG. 3.

FIG. 5 is a view showing a pair of pins separated from one another and indicating the interrelationship of the pins when installed in the rotor arm.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, the rotor of the present invention includes a core 11 which is provided with a central hole 12 for mounting the rotor on an associated drive shaft. The rotor is provided with arms 13 which extend radially outward from the axis of the rotor and which include trunnion pin support portions 14a, 14b, 14c and 14d. The portions 14 are each drilled to form a pair of intersecting holes. The holes 16-17; 18-19; 21-22; and 23-24 are formed in arms 14a, 14b, 14c and 14d, respectively. It is to be noted that the holes are all formed with their centerline lying on a plane which is perpendicular to the axis of rotation of the rotor. The holes of adjacent arms are in line with one another as, for example, the holes 17 and 18 are in line, the holes 19 and 21 are in line, 22 and 23 are in line, and 24 and 16 are in line. A pair of trunnion pins 26-27; 28-29; 31-32 and 33-34 are inserted in the openings 16-17, 18-19, 21-22 and 23-24, respectively. One end of each of the pins extends beyond the surface of the arms whereby the pin ends of adjacent arms form a trunnion. A swinging bucket or carrier 36 is suspended on the ends of the pins of adjacent arms. The carrier includes a slot which rides over the ends of the pins until it seats on pins to thereby support the bucket or carrier in swinging relationship whereby when the rotor spins, the buckets swing in a plane perpendicular to the axis of rotation.

Referring more particularly to FIGS. 3, 4 and 5, the relationship of each pair of pins carried on the members 14 is illustrated. Each of the pins includes a cylindrical body 41 which is stepped at 42 to provide a shoulder 43 and a surface 44. When a pair of pins is inserted in the intersecting holes of member 14, each is oriented so that the flat surfaces 44 are in face to face relationship. The shoulders 43 of one pin abut against the side edge of the other pin and vice versa whereby further movement of the pins outwardly is prevented.

It is to be understood that the rotor may comprise a rotor having four outwardly extending arms as shown in the figure or the rotor may have other numbers of arms with the end portions 14 having configurations such as to be provided with intersecting holes to receive the holding forces for the pins are centrifugal forces.

Manufacturing tolerances are not critical. The rotor and pins are simple and inexpensive to manufacture.

I claim:

l. A centrifuge rotor comprising a core for mounting the rotor on a drive shaft for rotating the rotor about its axis of rotation, a plurality of spaced arms extending radially outward from the axis of rotation, a pair of intersecting holes formed in the ends of each of said arms, said holes lying in a plane perpendicular to the axis of rotation, one of said pairs of holes in each arm aligned with one of the holes in one adjacent arm and the other aligned with one of the holes on the other adjacent arm, trunnion pins disposed in each of said holes with one end extending outwardly from said arms towards the outwardly extending pin of an adjacent arm to form a trunnion for supporting a carrier, the

2. A centrifuge rotor as in claim 1 wherein said pins are right circular cylinders.

3. A centrifuge rotor as in claim 1 wherein the arms terminate in enlarged portions.

IF k 

1. A centrifuge rotor comprising a core for mounting the rotor on a drive shaft for rotating the rotor about its axis of rotation, a plurality of spaced arms extending radially outward from the axis of rotation, a pair of intersecting holes formed in the ends of each of said arms, said holes lying in a plane perpendicular to the axis of rotation, one of said pairs of holes in each arm aligned with one of the holes in one adjacent arm and the other aligned with one of the holes on the other adjacent arm, trunnion pins disposed in each of said holes with one end extending outwardly from said arms towards the outwardly extending pin of an adjacent arm to form a trunnion for supporting a carrier, the other end of each of said pins including a stepped portion defining a surface and a shoulder, and said other end of the pins in each pair of holes being oriented to overlap with said surface of each in face to face relationship and the shoulders abutting a side of the cooperating pin.
 2. A centrifuge rotor as in claim 1 wherein said pins are right circular cylinders.
 3. A centrifuge rotor as in claim 1 wherein the arms terminate in enlarged portions. 